1. Field of the Invention
This invention relates to a winding spindle for simultaneously winding up a plurality of web strips alongside each other with the same web tension. The winding spindle includes a plurality of support and drive rings mounted for free rotation on the spindle. The support and drive rings are able to carry and drive winding cores, which have been slipped on the winding spindle. The winding cores are able to be non-positively coupled, by means of their lateral annular flanks, with thrust washers, which are connected slidingly and in a torque transmitting manner with the winding spindle, and are acted upon by a thrust.
2. Description of Related Art
In the winding spindle disclosed by German patent 3,615,479, a core support ring is gripped between two thrust rings. Between two adjacent support and drive rings, there is, in each case, a spacer sleeve supporting the same. A terminal thrust ring abuts, via a terminal thrust ring, on an annular collar on the winding spindle, while a thrust ring arranged on the other end of the winding spindles abuts against an actuating ring, which is subjected to a thrust in the axial direction by a tensioning means. Depending on the thrust applied by the tensioning means, the support and drive rings may be connected frictionally, via the thrust rings, with the winding spindle. However, since the thrust is applied from one end of the winding spindle via the actuating ring, owing to the friction of the elements (by which the thrust is transmitted) arranged in an axially sliding manner on the winding spindle, the thrust decreases from one support and drive ring to the next, so that the support and drive rings are coupled with the winding spindle in a manner involving decreasing friction and, thus, decreasing torque. In the known winding spindle, this phenomenon may be accentuated by the fact that, owing to the frictional engagement, or even positive interlocking engagement, of the support and drive ring, the winding core may impede the tensioning thrust applied via the actuating ring, to a greater or lesser extent. Consequently, the support and drive rings located at the opposite end of the winding spindle from the actuating ring will not be acted upon by a sufficiently powerful thrust from the associated thrust rings. Consequently, these support and drive rings tend to be connected with the winding spindle by an irregular and uncontrolled coupling.
Furthermore, in the winding spindle disclosed in German patent 3,615,479, a plurality of axial grooves are machined into the winding spindle at equal spacings about its circumferential face, in which a pressure hose is placed. The friction pads are applied to the inner wall side of the support rings, and thus transmit a torque to the support rings and to the winding core thereon. This application of radial thrust to the support rings, for the transmission of the torque necessary for winding, ensures a more even pressing of the frictional pads, and thus a more even torque, along the width of winding.
However a precondition for this is that all the support rings slipped onto the winding spindle must have a very accurately sized internal diameter. Major differences cause different frictional forces and, therefore, torques, since the frictional pads, which are not very flexible, are then applied with different forces to the inner wall of the support rings.
A further disadvantage of the radial action on the support rings is the different degree of wear of the frictional pads. If a certain size of material has been wound up for a prolonged period of time, the support rings which are in engagement are subjected to a larger amount of wear than the rings which have not been in engagement. If a different size of material, i.e., one which has a different effective width, is then wound up, the frictional pads are not able to come into such firm engagement with the inner wall face of the support rings at positions where there has been greater wear. This, in turn, leads to different amounts of torque in relation to the winding breadth.
A further disadvantage is that conventional combinations of frictional materials do not have a constant frictional behavior. In fact, when high torques are to be transmitted, stick-slip effects occur. Such stick-slip effects lead to vibrations of the winding spindle and, therefore, it is not possible to transmit the torque regularly. The vibrations may, in an extreme case, lead to an interruption of the clamping engagement with the winding core.
Satisfactory operation of the conventional winding spindle is possible if only a single winding core is held on it, because the core then evens out the torques transferred to it by the support and drive rings along its length. However, the total torque to be transferred by the support and drive rings to the winding core must be able to be reproducibly set, in order to not to exceed a certain tension of the web. Such a setting of the torque, leading to slip, is, however, not possible, if the holding force due to the actuating ring decreases in an irregular, uncontrolled manner from one thrust ring to the next.
Conventional winding spindles may have a length of 2 meters and bear approximately 50 support and drive rings distributed along their lengths. A plurality of winding cores with small breadths may be mounted on such a winding spindle. The webs may be wound up in a plurality of working widths. For example, webs could be formed by longitudinal slitting of the single web. The different widths would be wound with different degrees of hardness or compactness, owing to the different web tensions. There is even a chance of breakage of the webs, or of extreme sagging of the webs, if the individual winding cores are not properly coupled with the winding spindle, because of the application to the actuating ring of torques of different size.
Therefore, one object of this invention is to create a winding spindle of the type initially mentioned, with support and drive rings which are able to be coupled with the winding spindle along the length thereof with an adjustable torque, which is substantially the same for each support and drive ring.